The advantages of tire chains have been known for many years. When needed, tire chains provide enhanced traction on mud, snow, and ice surfaces, both for moving and for stopping the vehicle. Also, tire chains are relatively inexpensive and do not affect vehicle ride, handling, fuel economy, or performance when they are not necessary, which is at least 99 percent of the time for 99 percent of the people in the United States.
Also known are the disadvantages of tire chains, which, assuming well designed chains are properly selected for a given vehicle, tend to fall into three categories. The first category is installation. The disadvantages within this category include the considerable time required for installation and the physical difficulty and discomfort involved, often under adverse weather conditions, darkness, or stress. They may further include, depending upon whether a jack is employed, safety considerations or the need to re-adjust the chains after the vehicle has been driven. These disadvantages are described further in the patents identified below and in other patents in U.S. Patent and Trademark Office subclasses 152/213R and 81/15.8. The second category of disadvantages is operation of the vehicle after the chains have been installed. These disadvantages include chain wear and breakage, limitations on vehicle speed, vibration and accelerated wear of the vehicle, possible damage to the vehicle resulting from breakage of worn chains, and damage to the pavement. These disadvantages are greatly amplified by operation of the vehicle on bare pavement. The third category is removal of the chains from the tire.
These three categories of disadvantages are directly related, in that solutions to installation and removal problems ameliorate problems during vehicle operation. This is because, as a practical matter, the ability to install and remove tire chains quickly and easily enables the user to remove them as soon as the vehicle reaches bare pavement, knowing that the tire chains can be readily reinstalled as soon as (or if) they are needed again. Theoretically, perfect solutions to the installation problems and removal problems would eliminate nearly all of the operating problems. That is, if tire chains could be installed instantly by a mere snap of the driver's fingers immediately before serious snow or ice are encountered, and removed in the same manner when no longer needed, their above-mentioned operating disadvantages would disappear.
Some solutions involve ramps having spaced lateral grooves. After the tire chain is laid out with its cross chains lying loosely in the grooves, the vehicle is driven onto the ramp. The grooves allow the cross chains to be adjusted to positions where the necessary degree of tension can be attained before the ends of the chain are connected. See, for example, Garey U.S. Pat. No. 2,022,804. Ramps are most efficiently used in pairs, one pair for each pair of drive wheels. A problem presented by ramps is the difficulty of stopping the vehicle at the desired position on the ramp. One approach to solving this problem is to provide a stop for the wheel, as disclosed for example in Rhoads et al U.S. Pat. No. 2,604,802. This approach is not always effective, because under actual conditions it is difficult for the driver to feel the stop through the vehicle and distinguish it from other bumps, and he or she may drive the vehicle over the stop. A better approach is to signal the driver that the vehicle has reached the correct position, as taught for example by Masegian U.S. Pat. No. 4,194,724. Another significant improvement in ramps was the provision for storage with the chain oriented on the ramp, which Planz U.S. Pat. 3,893,500, "Chain Caddy", accomplished by upstanding edges on the ramp.
Other solutions to the problems of installing tire chains involve tools for engaging end elements of the chain to facilitate handling. Examples are Nakata U.S. Pat. No. 4,210,036 (hinged elongated rod) and Dalaba U.S. Pat. 4,703,675 (i-shaped spring clip to hold end of chain to tire during rotation to wind chain on tire).
Other solutions avoid the use of a jack or a ramp by applying a tire chain configured so that its ends can be connected with the cross chains nearest the ends outside the footprint of the tire and no chain beneath the footprint. This involves a compromise between ideal spacing between cross chains and achieving proper tension, and usually requires driving and stopping the vehicle after the tire chains have been installed and re-adjusting then. Also, a popular way of accomplishing this installation is to use a large hoop as an integral part of each tire chain. The hoop makes the tire chain difficult to store and handle and may require the user to hug the tire when connecting its opposite ends at the inner sidewall.
Despite the large number of patents directed to solving the problems of installing a tire chain, there remains a need for a single system which is capable of performing all of the following functions:
(a) storing an oriented tire chain having conventional side chains;
(b) handling and positioning the ramp and chain with respect to the tire before the vehicle is driven;
(c) correctly positioning the tire with respect to the chain when the vehicle is stopped;
(d) placing the chain, untwisted, on the tire in approximately the correct position;
(e) adjusting and tensioning the chain;
(f) ascertaining the location of the fastening elements at the end of the chain; and
(g) positively connecting those elements.
Such a system should accomplish the foregoing in the following manner:
(h) without fumbling or unsuccessful attempts by the user;
(i) while minimizing or eliminating contact of the user's hands with the chain, or the user's body with the ground or snow;
(j) without requiring exceptional mechanical ability, strength, or dexterity on the part of the user;
(k) simply, reliably, and inexpensively; and
(l) quickly. Generally speaking, the last requirement, "quickly", embraces many of the other requirements and will be the major factor determining the efficacy of the system.